Random insertion of introduced DNA into the genome of a host cell can be lethal if the foreign DNA disrupts an important native gene or regulatory region. Even if a random insertion event does not impair the functioning of a sequence in a host cell, the expression of an inserted foreign nucleotide sequence may be influenced by position effects caused by the surrounding genomic DNA. In some cases, the nucleotide sequence is inserted into a site where the position effect suppresses the function or regulation of the introduced nucleotide sequence. In other instances, overproduction of the gene product may have deleterious effects on a cell.
For example, in plants, position effects can result in reduced agronomics, additional costs for further research, creation of additional transgenic events, slowing product development. For these reasons, efficient methods are needed to target the insertion of nucleotide sequences into the genome of various organisms, such as plants, at chromosomal positions that allow for the desired function of the sequence of interest.